This is an application for an ADAMHA Research Scientist Development Award (RSDA) My long-standing interest in the neural basis of behavior has driven me to pursue an academic career as a neuroscientist. I am requesting this award because I am at a critical stage in my career. I recently obtained my first appointment as a tenure-track faculty member. Consequently, my institutional obligations have increased, and I have less time for research. I am, however, at a point where I need to develop scientifically. I need to collaborate with others and acquire skills, so that my research will not be limited by my technical abilities. Additionally, I need to interact with other faculty members and broaden my research program. Interactions will occur between myself and other members of the Physiology Department. Additionally, I will interact with members of the Fishberg Center for Neurobiological Research. Thus, in recent years Mt. Sinai has made a major commitment to the study of mental health. This interest has been reflected in recruitment policies; e.g., there are 6 Neuroscience faculty members with primary appointments in the Department of Physiology, and 9 faculty members with primary appointments in the Fishberg Center. With this award I will increase my interactions with the well-established Neuroscience community that has formed at Mt. Sinai. In addition to enhancing my own scientific development, this award will benefit others that will train with me. My postdoctoral years were spent in a large lab that functioned as a supportive, collaborative unit. I prospered in this environment and tend to recreate it, by establishing an active laboratory that includes both graduate students and postdocs. This award, which will relieve me of most of my teaching and administrative obligations, will make a critical difference to my development as a scientist. Additionally, it will enable me to devote time to the training of others. The long term goal of my research is to characterize cellular and molecular mechanisms that endow organisms with the ability to adapt to changes in the external environment. Immediate experiments will determine how the mollusk Aplysia makes a switch between two types of related, but distinctly different, rhythmic behaviors. I have developed a model that postulates that switches from one behavior to the other result from the phasic activity of sensory neurons. These sensory neurons contain both primary neurotransmitters and modulatory peptide cotransmitters. My work is, therefore, relevant to studies of plasticity in any rhythmic behavior that must accommodate changes in the external environment in a coordinated fashion. Additionally, I postulate a novel conceptualization of the physiological significance of the presence of primary transmitters and cotransmitters in neurons triggering switches from one behavior to another. This data will help guide future studies of the role of neuromodulation in circuit selection, and may provide insights into dysfunctions of the nervous system that occur when cognitive processes necessary for the proper choice of behavior are perturbed, as is the case with obsessions and compulsions. Thus, this research is directly relevant to the mission of the NIMH.